Hi everyone,
For those of you just joining this thread, the technical support team has been merging reports of externally-stored libraries disappearing into this thread, as we have an ongoing investigation into this issue.
This issue primarily affects users running MacOS. A known workaround, with variable success, is to restart the Core machine and remount the storage before forcing a rescan of the Watched Folder location. We’ll post updates as soon as we have more information.